Release valve lever



Jan. 7, 1964 c. L. BUHRO RELEASE VALVE- LEVER Filed. Sept. 19. 1960 INVENTOR. 6%7A s Be United States Patent i 3,116,907 RELEASE VALVE LEVER Charles L. Bnhro, Racine, Wis, assignor to Walker Manufacturing Company, a corporation of Delaware Filed ept. 19, 1 -60, der. No. 56,792 2 Claims. (:Cl. 251-28h) This invention relates generally to jacks and more particularly to a release mechanism for positively controlling the rate of lowering of a hydraulic jack. While it may be used with various jacks it is especially adapted for use with the jack shown in U.S. Patent #2,837,222.

The rate of descent of a conventional hydraulic jack is a function of release valve opening. Ordinarily, the pressure release valve is opened by means of a force applied directly to the release valve actuator, the degree of control over the rate of descent of the jack depending upon the sensitivity of the applied force. However, positive control over the degree of opening the release valve of a hydraulic jack sufiicient, for example, to render foot operation practicable, is relatively difficult when the force is applied directly to the release valve. Therefore, in those conditions wherein a safety hazard is present due to inadvertent release or the load supported by the jack, there is a need for a hydraulic jack release mechanism that can be relatively positively controlled.

The present invention is directed to a release mechanism that is operable in two modes, selectively, so as to open the release valve at a controlled rate regardless of the force applied to the release lever, or alternatively, to open the release valve in relation to the force applied. The latter condition is desirable to facilitate lowering of the jack when it is unnecessary to control the rate of descent thereof.

Accordingly, one object of the present invention is an improved mechanism for eilecting release of a hydraulic jack.

Another object is a mechanism for positively controlling the rate of descent of a hydraulic jack.

Another object is a release lever operable in different modes to eifect lowering of a hydraulic jack at different rates.

Other objects and advantages of the present invention will become apparent from the following specification, claims and drawings wherein a release mechanism, in accordance with an exemplary embodiment of the present invention, is shown in operative association with a convent onal hydraulic jack.

A release lever til is shown operatively mounted on a hydraulic jack 12 such as the one shown in US. Patent #2537222. The hydraulic jack 12 comprises a base 14 having suitable legs 16 and 18 for stabilizing the jack against tipping. A manually operated hydraulic pump 2% including a piston 22 and pump handle 24 is supported on the base 14-, the pump 2-8 being connected to a main hydraulic cylinder 26 as by various valves and passages (not shown). The pump handle 24- is pivotally connected to the base 14 by a link in such a manner that pumping of the handle 24 efiiects concomitant reciprocation of the piston 22 to thereby elevate a ram (not shown) within the main operating cylinder 26.

The jack 13 has an upstanding release valve 3% with an upwardly extending actuator 31 that is operable clownwardly to effect release or opening of the valve to release the load sustaining hydraulic pressure in the main hydraulic cylinder '26 and lower the ram (not shown). Ordinarily, the release valve actuator 31 is operable by foot pressure thereon thereby to bias the actuator 31 downwardly with respect to the base 14- of the jack 12. As discussed hereinbeiore, the degree of control over the rate or" lowering obtained by this expedient is insuflicient angst? Patented Jan. 7, 1964 to accurately control the rate of descent of the ram in those applications where the load is relatively heavy or safety demands more positive control.

In accordance with the present invention, the release lever it? is of U-shaped configuration defined by a bight portion 46 and leg portions 42 and 44. The release lever it) is supported for rotation with respect to the base 14 as by a pair of pivotal supports or bolts 4d and 48 that extend through suitable apertures in the end portions 5t) and 52 of the legs 42 and 4d and through suitable bosses 54 and 56, respectively, on the base 14.

A stop bracket 60 is secured to the base 14 of the jack 12 as by a pair of bolts 62 and 64. The stop bracket 649 has a horizontally extending stop flange 66 for movement limiting engagement with a lower end portion 68 of a. rate adjusting screw "70. The screw '79 is thread ably engaged in a nut 72 that is secured to the juncture of the bight portion as and leg portion 42 of the lever 1Q, as by welding. It is to be noted that the nut '72 is displaced to one side of a center line drawn between and normal to the axis of the pivotal supports 46 and 4d of the lever 10. The screw 7t? has a head 74 to facilitate rotation thereof with respect to the nut '72 and a locking nut 76 to facilitate locking of the screw against rotation with respect to the nut 72.

A generally L-shaped bracket till has a downwardly depending flange 82 secured to the leg 42 of the lever ill as by welding, and a horizontally extending flange 84 in alignment with the actuator 31 of the release valve 35). Upon downward movement of the lever 10, the flange 84 of the bracket St) is engageable with the actuator 31 to eilect opening of the release valve 30.

Calibration of an index or controlled rate of lowering of the jack 12 is accomplished after installation of the lever it) on the base 14. The metering screw 7t) is advanced downwardly until the flange Ston the bracket 8% is spaced from the actuator 31 of the release valve 3i when the lower end portion 68 or" the screw '76 is en gaged with the stop flange 66 on the stop bracket 60.

The operating handle 24 of the jack 12 is then pumped to elevate the ram (not shown), and a load is applied thereto, for example, a load of several hundred pounds when the jack is to be used for lowering transmissions of an automobile. The lever 1th is then biased downwardly by a force applied directly to the head 74 of the screw 76 until the lower end portion 68 of the adjusting screw 7% engages the stop flange 66 of the bracket oil. The adjusting screw 76 is then rotated so as to retract the end portion 68 thereof upwardly, as seen in the drawings, until the flange 34 on the bracket 56% engages the actuator 31 of the release valve 34F and the ram (not shown) begins to descend. When a desired rate of descent is achieved, the lock nut 7% about the screw ill is tightened thereby establishing the controlled or index rate of lowering.

To lower the jack at the index rate, pressure is applied directly to the head of the rate screw it? which forces the release lever ill downwardly until the lower end portion 68 of the screw 7th engages the flange 66 on the stop bracket 6th. It is to be noted that engagement of the bottom or end portion 68 of the adjusting screw 7t) with the flange 66 positively limits further movement of the lever lll and therefore opening of the release valve 30, regardless of how heavy the foot applied pressure might be. Therefore, in this mode of operation, the preset of the rate adjusting screw '70 controls the rate of descent of the ram (not shown) of the jack.

When it is unnecessary to control the rate of descent of a load supported by the jack 12, the load can be rapidly lowered by stepping on the release lever 10 in the area of the juncture of the bight portion 443 with the leg portion 44. When pressure is applied, as by the foot,

to this portion of the release lever it}, the release lever 19 first pivots downwardly about its pivotal supports as and 3-8 until the lower end portion 63 of the adjustment screw 7 engages the stop flange d6. When this condition obtains, the lever ll? is supported at three points, namely, by the pivotal supports it and 48 and the lower end portion as of the screw 7'6 Upon the application of additional pressure to the lever Ill in the area of the juncture of the bight portion 4%? and leg 44 thereof, the lever ll) pivots or flexes about a line drawn generally between the pivotal support 43 and the end portion 68 of the adjusting screw 7%. As the lever i153 rotates or flexes about this new axis, the leg :2 twists and the flange 84 on the bracket is deflected downwardly, as shown by the dotted line position to bias the actuator 31 of the release valve 3% downwardly. In this manner the natural resilience of the release lever 16 is utilized to permit fiexure about the newly obtained axis to effect twisting of the leg portion 42. Twisting of the leg 42 effects downward movement of the flange S4 of the bracket iii? to bias the release valve actuator 31 downwardly beyond the index position reached upon engagement of the screw 7% with the stop 66 thereby opening the release valve 30 to effect lowering of the jacl; at a rate relatively faster than the index rate.

It is to be understood that the specific construction of the improved jack herein disclosed and described is presented for the purpose of explanation and illustration and is not intended to indicate limits of the invention, the scope or" which is defined by the following claims.

What is claimed is:

l. A release mechanism for controlling the rate of lowering of a hydraulic jack having a release valve with an actuator thereon the rate of lowering of said jack being related to movement of the release valve actuator towards the open position, said release mechanism comprising a release lever, means for supporting said lever for rotation about a first axis so as to engage and move the release valve actuator of the jack towards the open position, and stop means engageable with said release lever for limiting rotation thereof about said first axis and movement of the releasevalve actuator at an index position, said release lever being rotatable about a second axis angularly related to said first axis and intersecting the point of engagement with said stop means to effect additional movement of the release valve actuator beyond said index position. v

2. A release mechanism for controlling the rate of lowering of a hydraulic jack wherein the rate of lowering is related to movement of a release valve actuator towards the open position, said release mechanism comprising a release lever of generally U-shaped configuration defined by a bight portion having depending leg portions the ends of which are supported for rotation, re spectively, about a common axis whereby said lever is rotatable in a plane generally normal to the bight portion thereof to engage and move the release valve actuator of the jack towards the open position, an adjustable stop screw secured to the bight portion of said release lever relatively closer to one of the leg portions thereof than to the other leg portion, and a stop bracket engageable with said stop screw for limiting movement of said lever thereby to limit movement of the release valve actuator to an index position, said release lever being bendable about an extending between the point of engagement of said stop screw with said stop bracket and the pivotal support for the other of the leg portions of said release lever to effect movement of the release valve actuator towards the open position and beyond said index position.

References Cited in the file of this patent UNITED STATES PATENTS Trautman June 3, 1958 

1. A RELEASE MECHANISM FOR CONTROLLING THE RATE OF LOWERING OF A HYDRAULIC JACK HAVING A RELEASE VALVE WITH AN ACTUATOR THEREON THE RATE OF LOWERING OF SAID JACK BEING RELATED TO MOVEMENT OF THE RELEASE VALVE ACTUATOR TOWARDS THE OPEN POSITION, SAID RELEASE MECHANISM COMPRISING A RELEASE LEVER, MEANS FOR SUPPORTING SAID LEVER FOR ROTATION ABOUT A FIRST AXIS SO AS TO ENGAGE AND MOVE THE RELEASE VALVE ACTUATOR OF THE JACK TOWARDS THE OPEN POSITION, AND STOP MEANS ENGAGEABLE WITH SAID RELEASE LEVER FOR LIMITING ROTATION THEREOF ABOUT SAID FIRST AXIS AND MOVEMENT OF THE RELEASE VALVE ACTUATOR AT AN INDEX POSITION, SAID RELEASE LEVER BEING ROTATABLE ABOUT A SECOND AXIS ANGULARLY RELATED TO SAID FIRST AXIS AND INTERSECTING THE POINT OF ENGAGEMENT WITH SAID STOP MEANS TO EFFECT ADDITIONAL MOVEMENT OF THE RELEASE VALVE ACTUATOR BEYOND SAID INDEX POSITION. 